W6XAO, A Pioneering Television Station,
by F. Alton Everest

Several decades before commercial television
'rounded the corner', the Don Lee Broadcasting System was
actively broadcasting television images. This work started in
1930 and by November 1931, the television transmitter W6XAO was
on the air from the Don Lee Building, 7th and Bixel Streets, Los
Angeles [1062 West 7th to be exact].

On May 21st. 1932, the first television motion
picture was reproduced on a cathode-ray receiver in an airplane.
[Lubcke subsequently wrote this up in a paper reproduced in the
IRE Journal]

On May 14, 1933, filmed scenes of the
Long Beach Earthquake were broadcast a few hours after the event
[actually, the LB Temblor was on March 10, 1933].

The year 1936 marked my arrival on Harry R.
Lubcke's television research and development staff in the Don Lee
Building. The display of Cadillac and LaSalle motor cars on the
first floor gave no hint of what was going on upstairs. The KHJ
transmitter and television activity of 3 or 4 workers shared the
eighth floor. [at the time, KHJ was on 900 kc utilizing a
horizontal antenna strung between two self-supporting towers
anchored to the roof. KHJ later moved to a two tower DA site on
Venice Blvd.]

As my graduate work at Stanford was drawing to
a close, Dr. Frederick E. Terman, my close professor mentioned an
opening at the Don Lee television laboratory and asked if I was
interested. A recommendation by Terman to Harry Lubcke sealed the
job for me.

My first job was the design and construction
of a sine-wave oscillator covering 50 to 1000 kHz with 400 volt
peak-to-peak amplitude primarily for transmitter testing. Other
jobs covered receiver and transmitter design, adjustment and
testing. My work with Lubcke lasted only four months because of
an opportunity to join the Electrical Engineering faculty at
Oregon State University.

Lubcke (1905-1991) received his degree in
electrical engineering from the University of California in 1929.
Even before his graduation, he worked in Philo T. Farnsworth's
television laboratory in San Francisco. While there, he built,
operated and patented the first all-electric synchronizing,
scanning and blanking-pulse generator. He joined the Don Lee
system on December 31st 1931 [1930 ?]. During his later years he
was a prominent patent attorney in Los Angeles.

Don Lee television in 1936 was built around a
disc scanning system for motion picture film, the sole program
source. Figure 1 is a photograph of the film scanning equipment
and Figure 2 is a schematic of the system. The film traveling at
a constant rate of speed is sequentially scanned by light through
the holes of the scanning disc. The video signal from the photo
electric cell is amplified and passed on to the transmitter. The
holes in the disc (#80 drill) were not in a spiral but at a
constant distance from the center. The effect of the spiral was
achieved by constant film motion which provided the movement from
line to line. The light from the arc lamp fell on the disc at an
angle, reduced the effective spot size and giving a modest
improvement in image quality. The demotionizing lens directed at
the spot of light from a single spot on the photo-sensitive
surface of the photo cell to minimize the effect of
irregularities over the emission surface.

Fig 1

Fig 2

It took 5-7 minutes to being the sync motor up
to 3600 rpm speed upon application of standard voltage. When
hunting began, double voltage was briefly applied to pull it into
step, after which the standard voltage was applied. When the
motor was turned off, it took about 18 minutes for it to come to
rest. I remember turning the equipment off after an evening
broadcast, going down the elevator and walking [east] to Figueroa
Street before the motor whine became inaudible.

The pulses for synchronization were modulated
upon the carrier along with the video signal. During the frame
interval a synchronizing pulse is transmitted to stabilize the
24hz sawtooth generator of the receiver. This pulse was obtained
by the arrangement of Figure 3.

Fig 3

The slotted drum was driven from the film
drive train so that the two slots lined up with the light beam
every time a frame line passed.

The line synch pulses were obtained by
directing a beam of light onto holes a short distance from the
point where the picture light falls. The over-all composite video
signal (the rectified carrier) looked something like the
idealized sketch of Figure 4. The frame pulses were 24/sec and
the line synch pulses were 7,200/sec (300 lines x 24 frames).

Fig 4

A photograph of the 1936 television
transmitter is shown in Figure 5. It was grid modulated with an
output power of 150 watts and operated on a frequency of 45 mHz.
The image was transmitted as negative for greater linearity.
Modest distortion of the synch pulses by the saturated bend of
the grid-modulation characteristic had negligible effect. By
adjusting the number of stages in the receiver the negative
picture was made positive... [description of amateurs, Don Lee TV
set plans, etc. omitted]

Fig 5

A well-publicized demonstration for the
general public was held in June 1936, shortly before my
departure. Long lines of people patiently waited to view the
wonder of 'pictures by radio' [several years later, off air TV
reception would be demonstrated at the Griffith Planetarium].

Fig 7

Figure 7 shows people straining to get a good
view of the 9-inch cathode-ray image (about 5x7 inch picture).
The transmitting antenna outside the eighth floor window which
sent the picture signal to the first-floor demonstration is shown
in Figure 8.

Fig 8

In the waiting lines, I spotted William S.
Klein, a fellow EE graduate of Oregon State. Bill applied for my
job and was hired. After the television work faded he became a
KHJ network and transmitter engineer until retirement.

Many other demonstrations were conducted on an
invitational basis from Lubcke's home in the Silver Lake
District, 3-1/2 miles from the transmitter. Old newsreels
provided much of the programming for W6XAO because the motion
picture industry was extremely wary about the future legal
implications. I remember one historical film, 'The Train Wreck'
which always lost frame hold as the train went in and out of a
tunnel.

Screen shots of 300 line image

During 1939, grandiose plans were
presented at the Los Angeles Planning Commission for a Mutual-Don
Lee Television Center on a hill to the rear of and above the
Hollywood sign overlooking the heart of Hollywood. This project
was later abandoned.